JPS60264088A - Controller of high frequency heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for preventing a dangerous situation such as a fire from occurring when a control circuit such as a microcomputer in a high-frequency heating device fails.

Conventional configuration and its problems In the conventional example, power supply control of an electronic lens was as shown in FIG. In other words, when the 5TART key is pressed, the key output signal 01 from the microcomputer 6 (hereinafter referred to as microcomputer) enters the key manual port 1,
determines that a start is required, outputs power supply relay control signal 02, turns on transistor Q1, and turns on relay 1.

The magnetron 8 starts oscillating. If this type of control is used, the power supply relay control signal 02 port of the microcomputer 6 may fail and the ONL signal is turned off, or noise may enter the key (K1) and the microcomputer determines that the 5TART key has been pressed, and 02 will be activated. It will be output and automatically oscillate. In other words, if a signal is always input to 1 for some reason, relay 1 is likely to turn ON and become in a very dangerous state.

Further, FIG. 4 shows a conventional example in which the above-mentioned problems have been solved. In this case, the normal operation is to first output a signal from the output port 03 of the microcomputer 6 and turn on the transistor Q3 when the cooking is ready. Next, when the G 5TART key is pressed, the signal from the output port 01 of the microcomputer 6 enters the SCR gate through Dl and turns on the SCRiON.On the other hand, the signal enters the human power port of the microcomputer 6 through D2 and enters the 5TART key on the master stove. It is determined that has been pressed.

Furthermore, since the microcomputer 6 determines that the 5TART key has not been pressed, it outputs a signal from the output port 02 to turn on the transistor Q2, causing current to flow through the relay, closing the contact, and causing the Macnetron 8 to start oscillating. However, in this case as well, the output port 03 of the microcomputer 6 may fail and the signal cannot be output, or the transistor Q3 may fail and the O'Nl
When the 5TART key is pressed, a signal enters 1 in the port 1-, and the microcomputer 6 starts to start, sending a signal from the output port 02 and turning on the transistor Q2. If you keep pressing the 5TART key in this state, the 01 signal enters the SCR gate through diode D1, turning on the relay. In other words, the relay is turned on while the 5TART key is pressed, causing an inconvenience.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and aims to prevent a dangerous state from occurring even when a control section such as a microcomputer breaks down.

Structure of the Invention In order to achieve the above object, the control circuit of the present invention has a structure in which a relay control circuit is configured with three transistors, and a safety circuit is created by using the resistance of the key input part such as the S'TART key. This has the effect of preventing a dangerous situation caused by a failure of the control ALW, reducing the cost of the conventional relay control section, and reducing the cost of the key human power section.

DESCRIPTION OF EMBODIMENTS Below, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, it is a perspective view of the main body of the microwave oven of one embodiment. 1 is the main body of the microwave oven, 2 is a door attached to the front of the main unit, 3 is a door handle for opening and closing the microwave oven, 4 is a part of the operation keys for setting the cooking contents and starting cooking, 5 is the contents etc. This is a display section that displays.

FIG. 2 is a block diagram. 6 is a microcomputer that is the center of the control section, and the information from the operation key section 4 is displayed on the display section 5.
and controls the relay control unit 7 to cause the Macnetron 8 to oscillate and heat the food 9.

FIG. 5 is a configuration diagram of an embodiment of the present invention. The relay control unit is composed of three transistors Q4, Q5, and Q6 and a relay, and controls the transistor Q6 by passing the signal from the 5TART key through the quartz D3. Also 5
Each key such as the TART key has an internal resistance Rx of several tens of Ω.
(For example, it is configured to have a resistance of 50Ω).

The operation in the configuration described above will be explained.

(Here, the output voltage of the microcomputer is assumed to be 9V) Masu, SW
The microcomputer 6 inputs the cooking contents input from SW1 to SW8, and outputs a signal of 01 when the cooking state is reached and applies a voltage to the emitter of Q4.

Next, when the microwave oven user presses the 5TART key, D
Through 3, point A becomes 9v and Q6 is ONL, thereby the base of Q4 is pulled to the ground (ov)i and Q4
turns on. Then, the collector of Q4 rises to almost 9v, so point A becomes 9v, and even if the 5TART key is released, Q6 remains ONL, and when the 5TART key is pressed again, the signal enters 1 through D2, so The microcomputer 6 assumes that the start button has been pressed and directly turns on the relay.
〇 Turn ON the output port of 02 to be FF, apply 9v to Q5, and turn it ON. At that time, Q6 is ON, so current flows from the relay drive voltage vRY through the relay coil to the collector emitter of Q5 and then from the collector to the emitter of Q6, closing the contact.

Further, when the signal 02 disappears, Q5 goes to 0FFL, and there is no current in the relay coil, and the contact opens to control the McNetron 8. This is the basic operation of the circuit of the present invention.

Next, I will explain in more detail. The key point of the present invention lies in the internal resistance of the key human power section.

Normally, in order to lower the resistance value, the internal pattern of a membrane-type key input part is made of a material with a low resistance value such as silver, and the resistance value is several hundred ohms or less, but in the present invention, the resistance value is several tens of kilohms It can be raised to .

FIG. 6 shows waveforms of 05 and 3 when SWS is pressed. A signal for capturing the key is output in the form of a pulse at 0φ. (The voltage at this time is VH = 9V) At this time, S
When W8 is closed, the potential VK at point B becomes H Vx =
If H, then VK≧VI)! It is sufficient that the following relational expression holds true. As an example
VIH:=6V, Vo=9V, Rx=50
If Ω is set to 6<−X RI RI+ 50, and R1≧100Ω, it is good to select a resistance value such as 150Ω for R1.

Next, the case of the 5TART key will be explained with reference to FIGS. 7 and 8. (
Similarly, internal resistance Rx-=rsoKΩ, R2=160
Think of it as Ω. In addition, the base current limiting resistance of Q6 is set to Rs = 3Ω and R4 = 16A'Ω as an example.) First, when cooking is not possible, that is, the
1 signal is not output, the voltage output from o5 (VH=9V) is the internal resistance 1 (x, R2 and R
The voltage VK at point B is divided by the resistor 3+R4, and the voltage VK at point B is V)I Vx = X (R2/(R3+R4))RX+(R
2/(R3+R4)) v 50K 4- (150x/(3+10x))v = X 1250x+12x = 1,74v (Fig. 8a). Therefore, the input of the microcomputer 6 is determined to be sufficiently smaller than the bell vu+(6y), and the microcomputer 6 determines that it is 5T.
Does not detect that the ART key has been pressed.

In other words, when the 01 signal is not output, 5TART
Even if the key is pressed, the microcomputer 6 shows no change at all. Next, let us consider a time when the cooking mode is enabled and 01 is output. At this time, when the 5TART key is pressed, as mentioned above, Q6 continues to turn on and Q4 turns on, so the potential of the black person becomes approximately 9V, and the potential vK of point B is -1 to H RX + R2 v 50 -1 change h = 6.75v, and the microcomputer 6 can determine that the 5TART key has been pressed (Fig. 8b).

From 8]f below, in the circuit of the present invention, the microcomputer 6 inputs the start signal only when it really needs the start signal (when the ol signal is output), and otherwise In this case, it is possible to ignore it in terms of hardware. In other words, even when the OL port fails and is not working, the microcomputer 6 does not output the signal 02 that controls the relay, so the relay does not operate at all. The relay will not operate unless the 5TART key is pressed while ol is being output, which has the effect of preventing a dangerous state from occurring.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) Compared to the conventional configuration, it is possible to prevent a dangerous state from occurring due to a failure of the control unit, and a safer control device can be obtained.

(2) A safer relay control circuit with a simpler configuration than conventional circuits can be obtained, resulting in cost reduction.

(3) Since the manual force part of the key has an appropriate internal resistance, in the structure of a membrane switch, etc., the switch ≦ can be formed from an inexpensive material such as carbon instead of silver, resulting in a significant cost reduction.

(4) Since the key manual part has an appropriate internal resistance, a control device that is resistant to external impulse noise can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the main body of a microwave oven which is an embodiment of the present invention, Fig. 2 is a block diagram of the structure of the same embodiment, Figs.
Figure 6 is a circuit diagram of a conventional relay control unit, Figure 6 is a circuit diagram of a relay control unit according to an embodiment of the present invention, Figure 6 is an input circuit for input keys other than the 5TART key and its voltage waveform diagram, Figure 7 is an input circuit diagram of the 5TART key, Figure 8 & is a voltage waveform diagram when the 5TART key is powered only when it is not possible to start, and Figure 8 is a voltage waveform diagram when the 5TART key is powered only when it is possible to start. be. 4. Key human resources department, 6. Microcomputer, γ
・Relay control section, 8 magnetron. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure 4 Figure 5 Figure 6 [ Figure 7 Figure 8

Claims (1)

[Claims] A microcomputer that controls high-frequency heating, a relay control section that uses the microcomputer to intermittent the high-frequency heating, and an operation section that gives the microcomputer a type of control method and an instruction to start the control, and when the relay control section starts operating. Signals from the operation unit and microcombi,
- High-frequency heating with a configuration in which the input impedance of the operating section is variably started when the heating is enabled and when the heating is disabled by calculating the logical product of the signals from the input signal. Device control device.